A variety of techniques are available for providing visual displays of still or video images to a user. One form of display is a scanned beam display. In one example of a scanned beam display, a scanning light source outputs a beam of coherent light that is reflected by a mirror in a MEMS scanner onto a viewer's retina. The scanned light enters the viewer's eye through the viewer's pupil and is directed onto the retina by the cornea and lens. The intensity of the light from the light source is modulated as the beam is scanned horizontally and vertically so that the viewer perceives an image. In other examples, the scanning source may include one or more modulated light emitters that are rotated through an angular sweep to scan the light onto the viewer's retina.
A typical requirement of scanned beam displays has been the need to collimate the light into a beam having a relatively small numerical aperture, i.e., a small divergence angle, prior to scanning the beam across the field-of-view. Unfortunately, providing a collimated, low numerical aperture beam of light frequently employs relatively expensive coherent light sources such as lasers, or edge-emitting light emitting diodes (“EELED”). Such collimated light sources may result in low optical efficiency and have the effect of producing a dimly lit display. Additionally, conventional scanned beam displays may require a relatively complex set of optics to deliver a scanned beam image.